Refrigerating apparatus



July 14, 1936.

F. H STlENINGv REFRIGERATING APPARATUS Filed Aug. 5, 19.34

Power Supply lVNVENTOR fwd? 144 BY.6I

anal @flu/ A TORNEY ParentalA July l14, 19'36 UNITED STATES .PATENT OFFICE of one-half to Elmer A. Hambur Pittsburgh,

Application August 3, 1934, Serial No. 738,225

3 Claims.

My invention relates to refrigeration, and more particularly is directed to refinements in refrigerating apparatus of the compression type.

Refrigerating apparatus of the sort with which I am primarily concerned includes in brief a motor-driven pump, a refrigerant, a condenser, an evaporator, a thermostatic control device, an expansion valve or a float valve, and a check valve. linv service the'pump compresses the reirigerant in gaseous state, and feeds it into the condenser, in which it is liquefied; subject to the control of either an expansion valve or a float valve, the liquid refrigerant is introduced into the evaporator; in the evaporator the refrigerant vaporizes, with the consequence and effect that heat isv abstracted from the surrounding atmosphere and the desired refrigerating effect is produced; and the'vaporized or gasiiied refrigerant is drawn from the evaporator, through the check valve, and into the pump. Thus, the re frigerant ows through a cycle; the operation of the apparatus is automatic, and, excepting the intermissions-eif'ected in known manner by the tlierrnostatic` control device, the operation is continuous.

Ordinarily the compression of the refrigerant is effected by a reciprocating pump, or a pump of the rotary vane type, and lt-has been realized, hitherto, that advantageously such pump and its propelling electric motor may be enclosed in a hermetically sealed casing or dome. Characteristically, the pump requires a relatively rapid circulation of lubricating and sealing oil, and to this end it has been the practice to provide an oil reservoir or sump in the sealed dome. During operation there is, within the dome, a continuous circulation of oil from the reservoir, through the pump, and back to the reservoir, and, in

`some cases, the passage of the oil from the pump to the reservoir is by way of external cooling coils or the like. The gasifledrefrigerant flowing from the evaporator is drawn immediately into the pump; the pump compresses the refrigerant and discharges it in gaseous state nd at superatmospheric pressure into the ch mberof the dome lying above the oil reservoir, whence the refrigerant flows into the lcondenser; in the condenser the refrigerant is liquefied, and then -fed by a return pipe into the reservoir', already mentioned. And from this reservoir the refrigerant, under the relatively high pressure existing in the dome, ows to the evaporator,subject,l of course, to the iiow regulation of an-expansion valve or y a iioat valve. The liquid refrigerant is of diierent specinc 'gravity than the pump-lubricating oil, and naturally the two liquids stratify in the reservoir, whereby it is possible to withdraw the oil and liquid refrigerant in independent streams. 'Ihe refrigerant may comprise sulphur dioxide, which has a specic gravity of approximately 1.4 5 when in liquid state, and the lubricant may comprise a highly reiined, colorless mineral oil of approximately .90 specific gravity. "All this is known practice.

It is further coinmon'v practice among some l0 manufacturers to employ an expansion valve for the regulation of refrigerant iiow into the evaporator. Certain objections, however, are found in such use of an expansion valve. For example,

an expansion valve essentially is a relatively l5' costly instrumentdelicate and liable to failure. Frequently, an expansion valvewill stick" in service, allowing too much refrigerant to ow into the evaporator coils, in consequence of which the suction lineofthe compressor becomes frosted. 20 Furthermore, the expansion valve essentially is mounted in the open, upon or adjacent the evaporator, and, accordingly. a truly. sealed system cannot be obtained, since the valve necessarily includes gaskets, screwed unions, soldered unions, 25 or other types of unions subjected to the open atmosphere and' tending to leak. Additionally, in the use of an expansion valve, the evaporator coils are only partly filled with liquid refrigerant-the so-called dry system-and manifestly 3o the heat exchange efiiciency of the evaporator is correspondingly low, substantially as vthe eiliciency of a boiler is low when its tubes are only partially lled with water.

Among other manufacturers it is the practice to use a oat valve device forregulating the ilow of refrigerant. The usual float valve device in- ,cludes a container which is sealed in the-feed line of the evaporator; in this container a pool of liquid refrigerant is maintained, anda iioat, responsive to the level of the pool, controls an outlet communicating with the evaporator. Manifestly, such structure kadmits of an absor4 lutely sealed, economical construction; the iioat valve operates with-the evaporator iiooded or fully chargedwith liquid refrigerant, and eliminates the objections and diiiiculties attending the use of an expansion valve. Unfortunately, howv ever, there is a tendency for the iioat valve to become gas bound; that isin service it often happens that non-condensable gases collect in the float valve chamber and condenser, and restrict the flow oi' refrigerant into the float valve chamber, so that the oat is prevented from functioning in its intended capacity.

' unit, and seals Contrary to such practice, I organize the means for controlling the iiow of refrigerant to the Aevaporator in immediate associa ion with the f motor-compressor unit, in such above-noted objections are eliminated. And in nner that the consequence ofv such organization, together with certain refinements to be described, I obtain substantial economies inthe construction and operation of refrlgerating apparatus.

In the accompanying drawing, Fig. I illusrates, partly in vertical central section and part-v ly in side elevation,

the inlet and exhaust ports and passages of the unit are indicated schematically, and, for purposes of illustration, the refrigerating elements ordinarily combined with the unit are indicated diagrammatically on smaller scale. Fig. Ilis a sectional view of the base of the unit, as it appears on the plane lI-II of Fig. I.

Referring to Fig. I, the reference numeral I indicates in general a sealed motor.l compressor unit. In accordance with usual practice alluded to, an electric motor, including a stator 2 and rotor 3, is mounted within a dome or casing 4, and is adapted to drivepthe rotor 5 of a compressor or pump 5. Under the action of the pump 6, the gaseous refrigerant (S62) is drawn from the evaporator 1, tlrough suction line 8, check valve 9, inlet passage I0, and into the pump. The pump compresses the refrigerant and discharges it in gaseous state through port II and into the interior of the dome 4. Upon entering the dome 4, the compressed gaseous refrigerant passes into the upper end or portion of a condenser J3,- which is pneumatically cooled, by a fan I4, or by natural draft. Thev refrigerant is liquefied in the condenser I3, and then it flows into a reservoir or sump I2, providing a pool I5 of liquid SO2. In regulated amounts the liquid refrigerant is fed from the pool I5 andinto the supply pipe I8 of the evaporator 1. Upon entering the evaporator the refrigerant vaporizes and abstracts heat from the atmosphere surrounding the evaporator, thereby producing the desired refrigerating effect. In known man'ner a thermostatic control device I1, responsive to the temperature of the evaporator, or of the atmosphere surrounding the evaporator, is effective automatically to control the energizing of thel fanV I4 and motor 2, 3, whereby the desired temperature ofthe refrigeratedatmosphere is automatically maintained.

A continuous circulation of lubricant is required during the operation of the rotary compressor 8, and to this end a pool I8 of lubricant is provided in the sump I2. As has been above indicated, the lubricant may comprise a colorless mineral oil of approximately .90.. specific gravity, while the liquid SO: has a Ispecific gravity of 1.4. Accordingly,the two liquids stratify--the oil pool I8, of course, lying upon the pool I5-of liquid SO2. It so happens that the two liquids are more or less soluble in one another, the degree of solubility being variable with pressure and temperature. Accordingly, the upper pool I8 more accurately may be said to comprise an oil-rich body, and the lower pool I5 an SO2- rich body- A Lubricant from the upper-pool I8 fiows through a passage I9 into the compressor, and in known manner servefs to lubricate the moving parts of the motor and compressor. drawn between the relatively moving parts of the the compression chamber of the compressor, whence it is fed back to the a motor-compressor unit em- 'bodying the invention;

Tire lubricant iS pool I8. It may be remarked that the` relative positions of the passages I0, II, and I9 circumferentially of the compressor chamberyhave been conventionably modified for purposes of illustration in the drawing.

Advantageously, the feeding of liquid refrigerant to the evaporator 1 is controlledby means of instrumentalities organized within the dome 4,

and advantageouslyr such instrumentalities in- .clude a oat 20 mounted on an arm 24 in the reservoir to swing in vertical plane about a pivot 2|. While the float is naturally affected by the compound effect of the buoyancies of the two bodies of liquid I5, I8, it is so constructed asy to be more responsive to the level of the SO2. That is, I so design the float that it sinks or submerges in the oil-rich liquid I8 and rides or floats on the SO2-rich liquid I5, with the consequence and effeet that, regardless of the depth of the oil-rich stratum, the float rise and f all with the raising and lowering of the level' of the SO2-rich stratum. Y, l

The passage 22 for feeding liquid SO2 to the evaporator includes a valveconveniently a needle valve 23-Which is so organized with the'iloat arm 24 that, as the float 20 rises and falls, the valve is openedv and closed. Accordingly, the feeding of'refrigerant to the evaporator is automatically controlled and harmonized with the functioning of the other elements of the apparatus. Clearly, such structure cannot become gas bound in service.

In accordance with my invention I provide in the reservoir ofthe above-described apparatus a depressed region I2a. (Fig. II), whereby, in the region wherein the oat 20 is operable, the liquid SO2 is concentrated, or of greater depth and of more buoyant effect thanfelsewhere. Thus, the huantity of refrigerant required is minimized, while the effective buoyancy upon theiloat is concentrated, providing more accurate operation of the valve 23 in keeping the evaporator 'I flooded with liquid refrigerant.

^I contemplate that the motor-enclosing walls of the dome 4 may be formed of metal of high conductivity and may be so extended in area that all of the compressed gaseous refrigerant discharged by the compressor 6 may be condensed within the dome, thereby eliminating auxiliary external condensing means, such as are indicated at I3. In any case, however, much of the compressed refrigerant condenses immediately upon leaving the compressor, and rains upon the pool I8 of lubricant. These globules of liquid SO2 slowly sink through the pool I8 and ilnd their lkindred pool I5. The liquid SO2 is of little or no value in lsealing the pump, and for this reason it is desirable that as little as possible of the SO2 small enter the compressor with the lubricant, and thereby reduce its efficiency. I have observed a tendency for the precipitated liquid SO2, sinking through the pool I8, to be entrained with the lubricant entering the passage I9, and this accounts for the fact that in many cases the compressor efficiency vantageously, I provide a shed 25, or other inletguarding means, over the mouth of passage I9. whereby the SO2 globules sinking through the oilrich pool I8 in the vicinity of such mouth are deected. Accordingly, the liquid entering'the passage I9 is relatively free from SO2, and so far as possible conditions of operation are maintained uniform and efiicient.

It may be remarked that the lubricant which is lower than it should be. Ad- 65 is carried with the SOI-rich liquid into the 75 apenas evaporator v'I is returned to the unit l by means oi' instrumentalities -well-knownto the art, and it is considered unnecessary to involve the present specification with these and other details of common knowledge. r v

I claim as my invention: l1. In refrigerating apparatus including in unit assembly within a sealed casing a motor. a compressor, a reservoir including a lower stratimi of liquid refrigerant andan upper stratum of lubricant, a passage for leading lubricant from said upper stratum to said compressor, a passage for leading refrigerant from said lower stratum, a

valve controlling said last-,mentioned passage, and

a float responsive mainly to the level of said lower stratum for operating said valve; the combination of means for protecting the mouth of said first-mentioned passage from precipitated quantities oi' refrigerant that tend, asl described, to entrain with the lubricant owing into said passage, and a depressedvregion in said reservoir for concentrating the body of liquid refrigerant beneath said oat.

2. In .refrlgerating apparatus including in unit assembly within a sealed casing a motor, a compressor, a reservoir including a lower stratum of liquid refrigerantv and van upper stratum of lubricant, a passage for leading lubricantfrom said upper stratum to said compressor, a passage vfor leading refrigerant from said lower-stratum, and a valve controlling said last-mentioned passage; the combination of a`oat pivotally mounted and angularly movable in `response to variations in the level of said lower stratum for operatin'g said valve, and a depressed region in Vsaid reservoir affording clearance for the angular movement oi' said iioat, while providing a concentration of the liquid refrigerant eiective upon the iioat.

3. In refrigerating apparatus including in unit assembly within a sealed casing a motor, a compressor, a reservoir including a-lower stratum of liquid refrigerant, and an upper stratum of lubricant, a lubricant passage leading from said upper stratum to said compressor, a refrigerant passage leading from said lower stratum, a valve control- Y ling said refrigerant passage, and a. oat for controlling said valve; the combination of means cooperating with the entrance of said lubricant passage (below the surface of vsaid upper stratum and above said lower stratum) for inhibiting precipitated refrigerant,'as it rains uponv and settles' through said upper stratum, from entering said lubricant passage.

. FRANK H. S'ITENING. 

